I am Sankar, working in Dubai. For the last 12 months, I have developed rough, black patches on my both index fingers, near the knuckles. The roughness prevails for a month or so, and then goes off for a month; again, it develops and stays for a month. It is continuing for 12 months now. The patches are itchy at times and give burning sensation at times. Why is this developing and what is the cure for this? I cannot send the photos now. Please help me.